static ssize_t w1_seq_show()

in slaves/w1_therm.c [2053:2123]

• 55 lines of code
• 10 McCabe index (conditional complexity)

static ssize_t w1_seq_show(struct device *device,
	struct device_attribute *attr, char *buf)
{
	struct w1_slave *sl = dev_to_w1_slave(device);
	ssize_t c = PAGE_SIZE;
	int i;
	u8 ack;
	u64 rn;
	struct w1_reg_num *reg_num;
	int seq = 0;

	mutex_lock(&sl->master->bus_mutex);
	/* Place all devices in CHAIN state */
	if (w1_reset_bus(sl->master))
		goto error;
	w1_write_8(sl->master, W1_SKIP_ROM);
	w1_write_8(sl->master, W1_42_CHAIN);
	w1_write_8(sl->master, W1_42_CHAIN_ON);
	w1_write_8(sl->master, W1_42_CHAIN_ON_INV);
	msleep(sl->master->pullup_duration);

	/* check for acknowledgment */
	ack = w1_read_8(sl->master);
	if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
		goto error;

	/* In case the bus fails to send 0xFF, limit */
	for (i = 0; i <= 64; i++) {
		if (w1_reset_bus(sl->master))
			goto error;

		w1_write_8(sl->master, W1_42_COND_READ);
		w1_read_block(sl->master, (u8 *)&rn, 8);
		reg_num = (struct w1_reg_num *) &rn;
		if (reg_num->family == W1_42_FINISHED_BYTE)
			break;
		if (sl->reg_num.id == reg_num->id)
			seq = i;

		w1_write_8(sl->master, W1_42_CHAIN);
		w1_write_8(sl->master, W1_42_CHAIN_DONE);
		w1_write_8(sl->master, W1_42_CHAIN_DONE_INV);
		w1_read_block(sl->master, &ack, sizeof(ack));

		/* check for acknowledgment */
		ack = w1_read_8(sl->master);
		if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
			goto error;

	}

	/* Exit from CHAIN state */
	if (w1_reset_bus(sl->master))
		goto error;
	w1_write_8(sl->master, W1_SKIP_ROM);
	w1_write_8(sl->master, W1_42_CHAIN);
	w1_write_8(sl->master, W1_42_CHAIN_OFF);
	w1_write_8(sl->master, W1_42_CHAIN_OFF_INV);

	/* check for acknowledgment */
	ack = w1_read_8(sl->master);
	if (ack != W1_42_SUCCESS_CONFIRM_BYTE)
		goto error;
	mutex_unlock(&sl->master->bus_mutex);

	c -= snprintf(buf + PAGE_SIZE - c, c, "%d\n", seq);
	return PAGE_SIZE - c;
error:
	mutex_unlock(&sl->master->bus_mutex);
	return -EIO;
}